Structural and Magnetic Properties of Iron Oxide Nanoparticles in Shells of Hollow Microcapsules Designed for Biomedical Applications

The functional hollow biodegradable microcapsules modified with the maghemite γ-Fe2O3 nanoparticles and the hollow spherical CoFe2O4/SiO2 nanocomposites were synthesized. Mössbauer spectroscopy data reveal that the main part maghemite nanoparticles have evident superparamagnetic behavior which is retained up to room temperature. This allows directing the microcapsules by an external magnetic field, which is very important for the problem of target drug delivery. On the other hand, the hollow spherical CoFe2O4/SiO2 nanocomposites with the small size particles do not show superparamagnetic behavior, but transit from magnetic to paramagnetic state by jump-like magnetic transition of the first order. This effect is a specific property of the magnetic nanoparticles isolated by an inert material. The method of synthesis can be modified with various bioligands on the silane surface, and such materials can have great prospects for use in diagnostics and bio-separation

HYPERFINE INTERACTIONS IN IRON BORATE FeBO3

For the FeBO3 single crystal, the values of isomer shift, quadrupole constant and magnetic hyperfine field were determined for over a wide temperature range.Исследования выполнены при финансовой поддержке РФФИ, проект № 19-29-12016-мк, в части мёссбауэровских исследований и теоретического анализа. Рентгеновские измерения проведены при поддержке Министерства науки и высшего образования РФ в рамках выполнения работ по Государственному заданию ФНИЦ «Кристаллография и фотоника» с использованием оборудования ЦКП (проект RFMEFI62119X0035)

LOCAL BLOOD FLOW AND MOTOR ACTIVITY JEJUNUM IN PATIENTS WITH EXTENSIVE PERITONITIS

Assessment of changes in local blood flow and motor activity of the jejunum in the early postoperative period  in patients with diffuse peritonitis helps to identify  intraabdominale complications and to clarify the indications for relaparotomy

Helical spin structure in the langasite family multiferroic Ba

The magnetic structure of the Ba3TaFe3Si2O14 multiferroic of the langasite family has been studied using the Mössbauer spectroscopy and theoretical analysis within the full Hamiltonian of the combined hyperfine magnetic dipole and electric quadrupole interaction in the ground and excited states of 57Fe nuclei. The model is based on an antiferromagnetic triangular magnetic lattice with a 120° orientation of the iron spins in the ($a,\ b$ )-plane, which occurs below the Néel temperature $T_{N}=27.2\ \text{K}$ . It was found that during translation along the c-axis, the magnetic moments of iron ions in triangular clusters rotate at an angle of $51.4^\circ$ . This angle remains constant with further translation, and a helical magnetic structure with a magnetic cell period of about 7c is formed. Excited states of magnetic moments arising due to a finite temperature are also considered. It has been established that the helical structure is well described by the proposed model in the entire temperature range T < TN

Tuning of Electronic and Vibrational Properties of Transition Metal Selenides TSe₂ (T = Os, Ru) and Their Metallization under High Pressure

We present a systematic analysis of electrical properties of two transition metal selenides OsSe2 and RuSe2 under conditions of low temperature down to 1.8K and external pressure up to 43 GPa. Both compounds have a pyrite-type crystal structure under ambient conditions and, according to Raman spectroscopy, do not undergo phase transitions up to the highest pressures. OsSe2 and RuSe2 undergo semiconductor-to-metal transitions at pressures up to 15 GPa. Further increase in pressure leads to the appearance of a superconducting transition at low temperatures. At 40 GPa, the critical temperatures of the superconducting transition reach maximum values of 5.5 and 6K for RuSe2 and OsSe2, respectively. © 2020, Pleiades Publishing, Inc

Mutual orientation of electric intracrystalline and magnetic fields in iron borate single crystals

X-ray structural analysis, Mssbauer spectroscopy, and ab-initio calculations were used to study the structural properties and refine the orientation of intracrystalline fields in FeBO3 crystals in the region of the magnetic phase transition. It was found that in the temperature range of 293 - 403 K, the trigonal lattice parameters increase monotonically. Analysis of the electron density distribution maps did not show visible local disordering over the entire investigated temperature range. It was found that iron borate has an axially symmetric electric field gradient (EFG), whose main axis is directed along [001]. This orientation is maintained above and below the Neel point. In magnetically ordered state of the crystal, the main axis of the EFG is orthogonal to the direction of the hyperfine magnetic field at iron nuclei. The results obtained will be used to develop a theoretical model of the formation of hyperfine structure in iron borate, which is important for applications of such crystals in the synchrotron technologies of a new generation

Structural Transitions in Elemental Tin at Ultra High Pressures up to 230 GPa

The crystal structure of elemental Sn was investigated by synchrotron X-ray diffraction at ultra high pressures up to ∼230 GPa creating in diamond anvil cells. Above 70 GPa, a pure bcc structure of Sn was observed, which is stable up to 160GPa, until an occurrence of the hcp phase was revealed. At the onset of the bcc-hcp transition at pressure of about 160GPa, the drop of the unit cell volume is about 1%. A mixture of the bcc-hcp states was observed at least up to 230GPa, and it seems that this state could exist even up to higher pressures. The fractions of the bcc and hcp phases were evaluated in the pressure range of the phase coexistence 160–230 GPa. The difference between static and dynamic compression and its effect on the V–P phase diagram of Sn are discussed

The Condorcet paradox revisited

We analyze the Condorcet paradox within a strategic bargaining model with majority voting, exogenous recognition probabilities, and no discounting. Stationary subgame perfect equilibria (SSPE) exist whenever the geometric mean of the players' risk coefficients, ratios of utility differences between alternatives, is at most one. SSPEs ensure agreement within finite expected time. For generic parameter values, SSPEs are unique and exclude Condorcet cycles. In an SSPE, at least two players propose their best alternative and at most one player proposes his middle alternative with positive probability. Players never reject best alternatives, may reject middle alternatives with positive probability, and reject worst alternatives. Recognition probabilities represent bargaining power and drive expected delay. Irrespective of utilities, no delay occurs for suitable distributions of bargaining power, whereas expected delay goes to infinity in the limit where one player holds all bargaining power. Contrary to the case with unanimous approval, a player benefits from an increase in his risk aversion